Crossbar switching systems



March 28, 1961 F, TRACHSEL 2,977,421

CROSSBAR SWITCHING SYSTEMS Filed Au 22, 1956 United States Patent() CROSSBAR SWITCHING SYSTEMS Fritz Trachsel, Bern-Bumpliz, Switzerland, assignor to Chr. Gfeller A.G., Bern-Bumpliz, Switzerland Filed Aug. 22, 1956, Ser. No. 605,654

Claims priority, application Switzerland Nov. 3, 1955 7 Claims. (Cl. 17927.54)

The present invention relates to an improved cross-bar switch, in particular a device adapted to limit the path of the longitudinal members of a selector as used in automatic telephone systems and similar installations. A selector is known to include several longitudinal members which are designed as switchbars movable individually in their longitudinal direction in order to be able to establish electric connections between longitudinal members and cross-members of the selector.

The invention has for its object to limit the path of movement of the switchbars by checking it in such a way that neither abrupt jerks and knocks nor vibrations occur which would unfavourably affect the operation of the selector.

The cross bar switch according to the invention is principally characterized by a number of leaf springs each of which are attached at one end to one of the switchbars, a stationary traverse intersecting all leaf springs and having pivotally supported thereon a number of members, one each allocated to each switchbar and pivotally connected to the associated leaf spring, the length of the pivotal members being so dimensioned as to draw the associated leaf spring with its one flat side towards said traverse in either end position of the switchbars, and thus brake the respective switchbar.

Further features of the invention will appear from the following description and claims, taken in conjunction with the accompanying drawing which shows by way of example one form of embodiment incorporating the invention.

-Fig. l is a part-front view of a crossbar switch;

Fig. 2 is a lateral view thereof, partly in cross-section taken on the line IIII of Fig. 1;

Fig. 3 shows a sectional view taken on the line III-III of Fig. 1.

Referring to said annexed drawing, the selector includes several vertically disposed switchbars 10, of which only two are shown in Fig. 1. Each of said switchbars consists of an electrically insulating, preferably transparent carrier 11, and electrically conducting strips 12 which are embedded in longitudinal grooves of the respective carrier 11 and have each a row of contact teeth 13. Fig. 1 shows two contact strips 12 in each switchbar, although a larger number of such strips or even only a single one may be provided. The contact teeth 13 are adapted to cooperate with the contact elements (not shown) of the cross-members (also not shown) of the selector. In a way not shown the switchbars are guided lengthwise so as to be capable of being individually moved up and down independently of each other. The downward movement may, for instance, take place by gravity, while for the upward movement each of the switchbars 10 may have an electromagnet (not shown) associated therewith.

Attached at top of each switchbar 10 is a leaf spring 14, one end of which is connected to the carrier 11 through rivets 15 or other connecting means. The frame (not shown) of the selector has attached thereto a horizontally extending stationary traverse 16 which intersects all leaf springs 14. The traverse 16 has a number of recesses 17 2,977,421 Patented Mar. 28, 1961 which are open at top and each arranged opposite one of the leaf springs 14. The recesses 17 are engaged by members 18 having at both ends an enlargement 19 and 20 respectively. Said members 18 and their enlargements 19 and 20 consist of pieces stamped out of flat material of substantially I-shaped base, as seen in Fig. 3. One end enlargement 19 of each member 18 engages over the edges of the related recess 17 and thus secures the member 18 from sliding out thereof. Each of the leaf springs 14 is provided in its middle section with a horizontal slot 21 through which the allocated member 18 protrudes. The end enlargement 20 secures the member 18 from sliding out of the slot 21. The enlargements 19 and slots 21 are so dimensioned that the former can be pushed therethrough in order to bring the members 18 into or out of engagements with the slots 21. The width of the slots 21 is greater than the thickness of the members 18 so as to enable these to swing in relation to the leaf spring 14, as shown in Fig. 2. The members 18 can also be swung up and down in the related recess 17.

The frame (not shown) of the selector includes furthermore a horizontally extending beam 25 fixedly mounted parallel to the traverse 16. The beam 25 has several leaf springs 26 attached thereto with one of their ends, while the other end thereof possesses a narrower end portion 27 adapted to enter a suitable slot at top of the adjacent leaf springs 14. Each of the springs 14 is pivotally connected in the manner described to one of the springs 26, whereby the springs 14 bear on the shoulders 28 of the springs 26 under the influence of their elasticity. The shoulders 28 are provided at the transition between the broader portion of the springs 26 and the narrower end portion 27 thereof.

Alternatively, instead of leaf springs 26, also inflexible members may be provided which are each connected by means of a joint to the upper end of the leaf springs 14 and to the beam 25. Both the last-mentioned rigid members as well as the illustrated leaf springs 26 serve as links for guiding the upper ends of the springs 14 when the switchbars 16 are moved up and down, as well as for operating at least one electric contact (not shown).

Upon movement of the switchbar 10 upwards or downwards, the related members 18 are swung in the corresponding direction, as indicated in Fig. 2. The length of the members 18, that is the distance apart of the enlargements 19 and 20, is so dimensioned, that both upon upward and downward swinging of the members 18, the associated leaf spring 14 will be drawn towards the traverse 16. One flat side of the leaf springs 14 thus comes to bear on traverse 16 when the switchbars have reached their upper or lower end position, whereby the switchbars will be braked gently and without abrupt knock.

The two extremities of each spring 14 are guided by the related switchbar 10 and by the spring 26 serving as a link, substantially in a straight or slightly curved line, while the middle section of the spring 14 is laterally deflected by the pivotal member 18 and drawn towards the traverse 16, contrary to the action of the elasticity of the spring 14 which tends to maintain its stretched, flat form. Consequently the elasticity of the spring 14 has for its effect that it automatically gets clear of the traverse 16 when the respective switchbar 10 has come to a standstill in its upper or lower position. The position then taken by the spring 14 is illustrated in Fig. 2 for the lower end position of the related switchbar 10.

The described automatic clearing of the springs 14 from the traverse 16 gives the advantage that vibrations of the latter, that possibly arise cannot be transmitted to the switchbars It If for instance one of the switchbars 10 is moved and then braked, the other switchbars 10 will not be shaken, so that no disturbing contact noises can set up by electric contact elements rubbing on each other.

It would be quite possible for the upper end of the leaf spring 14 to have no guidance by the springs 26 or the like, but then the automatic clearing of the springs 14 from the traverse 16 would not always beensured.

. What I claim is:

1. In a crossbar switch, a plurality of switchbar-s each mounted for longitudinal movement, a leaf spring secured to one end of each of the switchbars, a stationary member extending adjacent and transverse to each of the leaf springs, 21 braking element pivotally supported in each of the leaf springs and pivotally supported in the stationary member, the braking element being of such length as to draw the leaf spring into engagement with the stationary member upon longitudinal movement of the respective switchbar and thus damp the switchbar.

2. A crossbar switch according to claim 1 wherein each of the braking elements extends within slots in the respective switchbar and in the stationary member and means are disposed on the ends of each braking element for preventing release of the element from the slots.

3. A crossbar switch according to claim 2 wherein the slot in the stationary member is a 'groove in one end portion of the stationary member.

4. A crossbar switch according to claim 2 wherein each braking element is substantially I-shaped.

5. A crossbar switch according to claim 1 wherein each leaf spring is secured at an end portion to the respective switchbar and further comprising means engaging the other end portion of each leaf spring to cause the leaf spring to disengage from the stationary member when the respective switchbar is inoperative.

6. A crossbar switch according to claim 5 wherein said means includes a second stationary member and a guide 7 References Cited in the file or" this patent UNITED STATES PATENTS Graybill et a1. Aug. 23, 1949 OTHER REFERENCES German printed application, Steinbach, St. 8753 VIII a/21a German printed application, Bernutz and Steinbach, St. 8449 VIII a/21a 

